Method for producing a ceramic electronic component

ABSTRACT

A ceramic electronic component includes a ceramic body, an inner electrode, an outer electrode, and a connecting portion. The inner electrode is disposed inside the ceramic body. The end portion of the inner electrode extends to a surface of the ceramic body. The outer electrode is disposed on the surface of the ceramic body so as to cover the end portion of the inner electrode. The outer electrode includes a resin and a metal. The connecting portion is disposed so as to extend from an inside of the outer electrode to an inside of the ceramic body. In a portion of the surface of the ceramic body on which the outer electrode is disposed, the length of the connecting portion that extends in a direction in which the inner electrode is extends about 2.4 μm or more.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No. 13/287,255, now U.S. Pat. No. 9,490,055, filed on Nov. 2, 2011.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a ceramic electronic component and a method for producing the ceramic electronic component.

2. Description of the Related Art

In recent years, ceramic electronic components such as monolithic ceramic capacitors have been used in harsher environments than compared with before.

Ceramic electronic components used for mobile devices such as cellular phones and portable music players are required to withstand drop impacts. Specifically, even if electronic components undergo drop impacts, it is necessary that they will not easily become detached from mount boards and that cracks will not easily form in electronic components.

Electronic components used for in-vehicle equipment such as ECUs are required to withstand the shock of a thermal cycle. Specifically, even if mount boards undergo deflection stress caused when the mount boards are subjected to thermal expansion and contraction due to a thermal cycle, it is necessary that cracks will not easily form in ceramic electronic components and solder used to mount the electronic components.

To satisfy such requirements, it has been proposed that an outer electrode containing a resin be formed using a thermosetting conductive paste instead of a conventional firing conductive paste. For example, WO2004/053901 discloses a ceramic electronic component including an outer electrode that is formed using a thermosetting conductive paste containing conductive particles with a high melting point, a metal powder with a melting point of 300° C. or lower, and a resin with a melting point of 300° C. or lower.

In recent years, there has been an increasing demand for a further increase in the bonding strength between an inner electrode and an outer electrode.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide a ceramic electronic component with high bonding strength between an inner electrode and an outer electrode.

A ceramic electronic component according to a preferred embodiment of the present invention includes a ceramic body, an inner electrode, an outer electrode, and a connecting portion. The inner electrode is disposed inside the ceramic body. The end portion of the inner electrode extends to a surface of the ceramic body. The outer electrode is disposed on the surface of the ceramic body so as to cover the end portion of the inner electrode. The outer electrode includes a resin and a metal. The connecting portion is disposed so as to extend from an inside of the outer electrode to an inside of the ceramic body. In a portion of the surface of the ceramic body on which the outer electrode is formed, the length of the connecting portion that extends in a direction in which the inner electrode extends is about 2.4 μm or more.

In one aspect of the ceramic electronic component according to a preferred embodiment of the present invention, the connecting portion contains the same metal as that contained in the outer electrode and the same metal as that contained in the inner electrode.

In another aspect of the ceramic electronic component according to a preferred embodiment of the present invention, the outer electrode contains a first metal component and a second metal component having a higher melting point than the first metal component, and the connecting portion contains the first metal component.

In still another aspect of the ceramic electronic component according to a preferred embodiment of the present invention, the first metal component contains Sn and the second metal component contains Ag.

In still yet another aspect of the ceramic electronic component according to a preferred embodiment of the present invention, the inner electrode contains Ni and the connecting portion contains a Sn—Ni alloy.

In still yet another aspect of the ceramic electronic component according to a preferred embodiment of the present invention, the width of a portion of the connecting portion located in the outer electrode is larger than the width of a portion of the connecting portion located in the ceramic body.

In a method for producing a ceramic electronic component according to yet another preferred embodiment of the present invention, a ceramic body is prepared that includes an inner electrode disposed inside the ceramic body and in which an end portion of the inner electrode extends to a surface of the ceramic body. An electrode layer is formed on the surface of the ceramic body so as to cover the end portion of the inner electrode, the electrode layer containing a resin, a first metal filler that contains a first metal component, and a second metal filler that contains a second metal component having a higher melting point than the first metal component. The electrode layer is heated to form, on the surface of the ceramic body, an outer electrode that contains the resin and the first and second metal components and that is disposed so as to cover the end portion of the inner electrode and a connecting portion that contains the first metal component and a metal contained in the inner electrode and that is disposed so as to extend from an inside of the outer electrode to an inside of the ceramic body.

In one aspect of the method for producing a ceramic electronic component according to a preferred embodiment of the present invention, in the heating step, the electrode layer is heated to about 480° C. or higher in a non-oxidative atmosphere.

In another aspect of the method for producing a ceramic electronic component according to a preferred embodiment of the present invention, in the heating step, the electrode layer is heated to a temperature of lower than about 800° C.

In still another aspect of the method for producing a ceramic electronic component according to a preferred embodiment of the present invention, the first metal component contains Sn, and the second metal component contains Ag.

In still yet another aspect of the method for producing a ceramic electronic component according to a preferred embodiment of the present invention, the inner electrode contains Ni.

According to various preferred embodiments of the present invention, a ceramic electronic component with high bonding strength between the inner electrode and the outer electrode is provided.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a ceramic electronic component according to a preferred embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a cross section that extends in the length direction L and the thickness direction T of the ceramic electronic component according to a preferred embodiment of the present invention.

FIG. 3 is a schematic sectional view taken along line III-III of FIG. 2.

FIG. 4 is a schematic sectional view taken along line IV-IV of FIG. 2.

FIG. 5 is a schematic sectional view of a V portion of FIG. 2.

FIG. 6 is a schematic sectional view for describing the production process of the ceramic electronic component according to a preferred embodiment of the present invention.

FIG. 7 is a photograph showing a partially enlarged cross section of a ceramic electronic component prepared in Experimental Example 8. Specifically, FIG. 7 is a scanning electron micrograph obtained by observing a portion of the ceramic electronic component prepared in Experimental Example 8 at an acceleration voltage of 15.0 kV with a magnification of 5000×.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An example of preferred embodiments of the present invention will now be described. Note that the preferred embodiments described below are merely examples. The present invention is not limited to the preferred embodiments described below.

In the drawings referred to in the description of preferred embodiments, components having substantially the same function are denoted by the same reference numerals. The drawings referred to in the description of preferred embodiment are schematically described, and the size ratio of objects drawn in the drawings may be different from that of actual objects. The size ratio of objects may also be different between the drawings. The specific size ratio of objects should be judged by taking the following description into consideration.

FIG. 1 is a schematic perspective view of a ceramic electronic component according to a preferred embodiment of the present invention. FIG. 2 is a schematic sectional view showing a cross section that extends in the length direction L and the thickness direction T of the ceramic electronic component according to the present preferred embodiment. FIG. 3 is a schematic sectional view taken along line III-III of FIG. 2. FIG. 4 is a schematic sectional view taken along line IV-IV of FIG. 2. FIG. 5 is a schematic sectional view of a V portion of FIG. 2. First, the structure of a ceramic electronic component 1 according to the present preferred embodiment will be described with reference to FIGS. 1 to 5.

The ceramic electronic component 1 includes a ceramic body 10. The ceramic body 10 preferably has a rectangular parallelepiped shape, for example. The ceramic body 10 includes first and second principal surfaces 10 a and 10 b that extend in the length direction L and the width direction W, first and second side surfaces 10 c and 10 d that extend in the thickness direction T and the length direction L, and first and second end surfaces 10 e and 10 f that extend in the thickness direction T and the width direction W.

In preferred embodiments of the present invention, the “rectangular parallelepiped shape” includes a rectangular parallelepiped whose corners and ridge lines are rounded. That is, a “rectangular parallelepiped” component includes any component having first and second principal surfaces, first and second side surfaces, and first and second end surfaces. Furthermore, depressions and projections may be partially or entirely formed on the principal surfaces, side surfaces, and end surfaces.

The ceramic body 10 is composed of a suitable ceramic material. The type of ceramic material constituting the ceramic body 10 can be suitably selected in accordance with desired characteristics of the ceramic electronic component 1.

For example, when the ceramic electronic component 1 is a capacitor (monolithic ceramic capacitor), the ceramic body 10 can be formed of a dielectric ceramic material. Examples of the dielectric ceramic material include BaTiO₃, CaTiO₃, SrTiO₃, CaZrO₃, MgTiO₃, MgTiO₃—CaTiO₃, TiO₂ and BaTiO₃—Nd₂O₃—TiO₂.

For example, when the ceramic electronic component 1 is a piezoelectric component, the ceramic body 10 can be formed of a piezoelectric ceramic material. An example of the piezoelectric ceramic material is a PZT (lead zirconate titanate) ceramic material.

For example, when the ceramic electronic component 1 is a thermistor, the ceramic body 10 can be formed of a semiconductor ceramic material. An example of the semiconductor ceramic material is a spinel-type ceramic material.

For example, when the ceramic electronic component 1 is an inductor, the ceramic body 10 can be formed of a magnetic ceramic material. An example of the magnetic ceramic material is a ferrite ceramic material.

As shown in FIGS. 2 to 4, inside the ceramic body 10, a plurality of first and second inner electrodes 25 and 26 each having a substantially rectangular shape are alternately arranged at regular intervals in the thickness direction T. The first and second inner electrodes 25 and 26 are parallel or substantially parallel to the first and second principal surfaces 10 a and 10 b. In the thickness direction T, the first and second inner electrodes 25 and 26 face each other with a ceramic layer 10 g therebetween. The thickness of the ceramic layer 10 g is, for example, preferably about 0.5 μm to about 10 μm.

The end portions of the first and second inner electrodes 25 and 26 are led to the surface of the ceramic body 10. Specifically, the first inner electrode 25 is exposed on the first end surface 10 e, and is not exposed on the first and second principal surfaces 10 a and 10 b, the second end surface 10 f, and the first and second side surfaces 10 c and 10 d. The second inner electrode 26 is exposed on the second end surface 10 f, and is not exposed on the first and second principal surfaces 10 a and 10 b, the first end surface 10 e, and the first and second side surfaces 10 c and 10 d. Specifically, the end portions of the first and second inner electrodes 25 and 26 are slightly depressed from the first and second end surfaces 10 e and 10 f, respectively.

The first and second inner electrodes 25 and 26 can be composed of a suitable conductive material, e.g., a metal such as Ni, Cu, Ag, Pd, or Au or an alloy containing at least one of the foregoing metals, such as a Ag—Pd alloy. In particular, the first and second inner electrodes 25 and 26 preferably contain Ni. Specifically, the first and second inner electrodes 25 and 26 are preferably composed of, for example, Ni or a Ni-containing alloy such as Ni—Cu.

The thicknesses of the first and second inner electrodes 25 and 26 are, for example, each preferably about 0.2 μm to about 2.0 μm.

First and second outer electrodes 13 and 14 are disposed on the surface of the ceramic body 10. Specifically, the first outer electrode 13 is disposed so as to cover the first end surface 10 e on which the first inner electrode 25 is exposed. The first outer electrode 13 is disposed so as to reach the first and second principal surfaces 10 a and 10 b and the first and second side surfaces 10 c and 10 d. The first outer electrode 13 is electrically connected to the first inner electrode 25.

The second outer electrode 14 is disposed so as to cover the second end surface 10 f on which the second inner electrode 26 is exposed. The second outer electrode 14 is disposed so as to reach the first and second principal surfaces 10 a and 10 b and the first and second side surfaces 10 c and 10 d. The second outer electrode 14 is electrically connected to the second inner electrode 26.

The first and second outer electrodes 13 and 14 each include a first conductive layer 15 and a second conductive layer 16. The first conductive layer 15 is disposed directly on the surface of the ceramic body 10. Specifically, the first conductive layer 15 is disposed so as to cover the first end surface 10 e or the second end surface 10 f and reach the first and second principal surfaces 10 a and 10 b and the first and second side surfaces 10 c and 10 d. Herein, the first conductive layer 15 may be disposed only on the first end surface 10 e or the second end surface 10 f.

The thickness of the first conductive layer 15 is, for example, preferably about 5.0 μm to about 70.0 μm.

The second conductive layer 16 is disposed on the first conductive layer 15. The first conductive layer 15 is substantially covered with the second conductive layer 16. The second conductive layer 16 is preferably composed of a plating film, for example. The second conductive layer 16 may be composed of a single plating film or a laminated body of multiple plating films. Specifically, the second conductive layer 16 is disposed on the first conductive layer 15 and may be composed of a laminated body of a Ni plating layer that also serves as a barrier layer and a plating layer that is disposed on the Ni plating layer and contains Sn or Au, which has good wettability. The thickness of each of the plating layers constituting the second conductive layer 16 is, for example, preferably about 1 μm to about 15 μm.

The first conductive layer 15 contains a first metal component, a second metal component, and a resin. In the first conductive layer 15, the first and second metal components are disposed in a resin matrix, and the first and second metal components provide conductivity of the first conductive layer 15. The first and second metal components may be alloyed with each other.

Since the first conductive layer 15 contains a resin, it is more flexible than a conductive layer composed of, for example, a plating film or a fired product of conductive paste. Therefore, even if the ceramic electronic component 1 is subjected to physical impact or the shock caused by a thermal cycle, the first conductive layer 15 functions as a shock absorbing layer. Thus, the ceramic electronic component 1 is not easily damaged and solder used to mount the ceramic electronic component 1 is also not easily damaged.

Preferred examples of the resin added to the first conductive layer 15 include thermosetting resins such as an epoxy resin and a phenolic resin.

The content of the resin in the first conductive layer 15 after curing is preferably about 46% to about 77% by volume, for example.

The melting point of the first metal component is relatively low and the melting point of the second metal component is relatively high. The melting point of the first metal component is, for example, preferably about 550° C. or lower and more preferably about 180° C. to about 340° C. The melting point of the second metal component is, for example, preferably about 850° C. to about 1050° C.

The first metal component is preferably composed of, for example, Sn, In, or Bi or an alloy containing at least one of the foregoing metals. In particular, the first metal component is more preferably composed of Sn or an alloy containing Sn. Examples of the alloy containing Sn include Sn—Ag, Sn—Bi, and Sn—Ag—Cu.

The content of the first metal component in the first conductive layer 15 after curing is preferably about 8% to about 18% by volume, for example.

The second metal component is preferably composed of, for example, a metal such as Ag, Pd, Pt, or Au or an alloy containing at least one of the foregoing metals. In particular, the second metal component is more preferably composed of Ag or a Ag alloy such as a Ag—Pd alloy.

The content of the second metal component in the first conductive layer 15 after curing is preferably about 19% to about 25% by volume, for example.

The first conductive layers 15 of the outer electrodes 13 and 14 are connected to the respective inner electrodes 25 and 26 through a connecting portion 18. The connecting portion 18 is disposed so as to extend from the inside of each of the outer electrodes 13 and 14 to the inside of the ceramic body 10. In the portion (end surfaces 10 e and 10 f) of the surface of the ceramic body 10 on which the outer electrodes 13 and 14 are disposed, the length L of the connecting portion 18 that extends in the direction (length direction) in which the inner electrodes 25 and 26 are led is about 2.4 μm or more, for example. The length L of the connecting portion 18 is preferably about 9.6 μm or less, for example.

The width W1 of a portion of the connecting portion 18 formed in each of the outer electrodes 13 and 14 is larger than the width W2 of a portion of the connecting portion 18 formed in the ceramic body 10.

The connecting portion 18 preferably contains the same metal as that contained in the outer electrodes 13 and 14 and the same metal as that contained in the inner electrodes 25 and 26. The connecting portion 18 more preferably contains the first metal component having a relatively low melting point. For example, in the case where the first metal component contains Sn and the inner electrodes 25 and 26 contain Ni, the connecting portion 18 preferably contains a Sn—Ni alloy.

A non-limiting example of a method for producing the ceramic electronic component 1 will now be described.

First, a ceramic body 10 including first and second inner electrodes 25 and 26 is prepared. Specifically, a ceramic paste containing a ceramic powder is applied in a sheet-shaped configuration by screen printing or other suitable process and then dried to produce a ceramic green sheet. Subsequently, a conductive paste for forming inner electrodes is applied on the ceramic green sheet in a predetermined pattern by screen printing or other suitable process. Thus, a ceramic green sheet on which a conductive pattern for forming inner electrodes has been formed and a ceramic green sheet on which a conductive pattern for forming inner electrodes is not formed are prepared. Note that a publicly known binder or solvent may be contained in the ceramic paste and the conductive paste for forming inner electrodes.

Next, a predetermined number of ceramic green sheets on which a conductive pattern for forming inner electrodes is not formed are stacked on top of each other. Ceramic green sheets on which a conductive pattern for forming inner electrodes has been formed are stacked thereon successively. A predetermined number of ceramic green sheets on which a conductive pattern for forming inner electrodes is not formed are further stacked thereon. As a result, a mother stack is produced. The mother stack may be optionally subjected to pressing in the stacking direction by isostatic pressing or other suitable process.

The mother stack is then cut into a plurality of green ceramic bodies each having a predetermined shape and size. The green ceramic bodies may be subjected to barrel polishing to round the ridge lines and corners thereof.

Next, by firing each of the green ceramic bodies, a ceramic body 10 is completed that includes first and second inner electrodes 25 and 26 disposed inside the ceramic body 10 and in which the end portions of the first and second inner electrodes 25 and 26 are led to the first and second end surfaces 10 e and 10 f, respectively. The firing temperature of the green ceramic bodies can be suitably set in accordance with the ceramic material and conductive material used. The firing temperature of the green ceramic bodies can be, for example, about 900° C. to about 1300° C.

A paste for forming outer electrodes is then prepared that contains a resin 17 c such as a thermosetting resin, a first metal filler 17 a containing a first metal component, and a second metal filler 17 b containing a second metal component having a higher melting point than the first metal component.

In this paste, the content of the first metal filler 17 a relative to the total weight of the first metal filler 17 a, the second metal filler 17 b, and the resin 17 c is preferably about 20% to about 40% by weight and more preferably about 22.0% to about 37.2% by weight, for example. If the content of the first metal filler 17 a is excessively low, a connecting portion 18 is sometimes not sufficiently formed. If the content of the first metal filler 17 a is excessively high, the amount of first metal filler 17 a that does not react with the second metal filler 17 b and is left in outer electrodes 13 and 14 increases. As a result, the outer electrodes 13 and 14 may be deformed, for example, due to heat applied during reflowing.

The shape of the first metal filler 17 a is not particularly limited. The first metal filler 17 a may have a spherical shape, a flat shape, or other suitable shape.

The average particle size of the first metal filler 17 a is not particularly limited and may be, for example, about 1.0 μm to about 10 μm.

In this paste, the content of the second metal filler 17 b relative to the total weight of the first metal filler 17 a, the second metal filler 17 b, and the resin 17 c is preferably about 30% to about 70% by weight and more preferably about 41.2% to about 64% by weight, for example. If the content of the second metal filler 17 b is excessively low, the conductivity of the outer electrodes 13 and 14 decreases and the equivalent series resistance (ESR) of the ceramic electronic component 1 may increase. If the content of the second metal filler 17 b is excessively high, the content of the resin 17 c in the outer electrodes 13 and 14 excessively decreases. As a result, the stress relaxation effect of the outer electrodes 13 and 14 may excessively degrade.

The shape of the second metal filler 17 b is not particularly limited. The second metal filler 17 b may have a spherical shape, a flat shape, or other suitable shape.

The average particle size of the second metal filler 17 b is not particularly limited and may be, for example, about 0.5 μm to about 5.0 μm.

In this paste, the content of the resin 17 c relative to the total weight of the first metal filler 17 a, the second metal filler 17 b, and the resin 17 c is preferably about 5% to about 40% by weight and more preferably about 9.8% to about 31.5% by weight, for example. If the content of the resin 17 c is excessively low, the stress relaxation effect of the outer electrodes 13 and 14 excessively degrade and thus impacts generated when stress is applied from the outside are sometimes not sufficiently absorbed by the outer electrodes 13 and 14. If the content of the resin 17 c is excessively high, the conductivity of the outer electrodes 13 and 14 decreases and the equivalent series resistance (ESR) of the ceramic electronic component 1 may increase.

As shown in FIG. 6, an electrode layer 17 is then formed by applying the above-described paste onto the surface of the ceramic body 10. The paste can be applied by various printing methods or a dipping method, for example.

Next, the electrode layer 17 is heated. The heating temperature of the electrode layer 17 is preferably higher than or equal to a temperature (temperature range in which the diffusion of the first metal component to the outside of the electrode layer 17 is facilitated) at which the crystalline state of an alloy of the first metal component and the second metal component changes thermodynamically. The heating temperature of the electrode layer 17 is, for example, preferably about 480° C. or higher. The electrode layer 17 is preferably heated in a non-oxidative atmosphere, e.g., a reducing atmosphere or a neutral atmosphere such as a nitrogen gas atmosphere. The electrode layer 17 is preferably heated in an atmosphere whose oxygen concentration is about 100 ppm or less, for example. By heating the electrode layer 17 to such a high temperature, the outer electrodes 13 and 14 that contain the resin and the first and second metal components and are disposed so as to cover the end portions of the inner electrodes 25 and 26 and the connecting portion 18 that contains the first metal component and the metal contained in the inner electrodes and is disposed so as to extend from the inside of each of the outer electrodes 13 and 14 to the inside of the ceramic body 10 are formed on the surface of the ceramic body 10.

If the heating temperature of the electrode layer 17 is excessively high, the first conductive layer 15 containing the resin 17 c is sometimes not suitably formed. Thus, the heating temperature of the electrode layer 17 is preferably lower than about 800° C. and more preferably about 650° C. or lower.

Finally, by forming a second conductive layer 16 by a plating method or other suitable process, a ceramic electronic component 1 can be completed.

As described above, since the outer electrodes 13 and 14 contain the resin 17 c in this preferred embodiment, the ceramic electronic component 1 is excellent in terms of impact resistance and resistance to a thermal cycle. In addition, the length L of the connecting portion 18 is preferably set to be about 2.4 μm or more, for example. This achieves high bonding strength between the inner electrodes 25 and 26 and the respective outer electrodes 13 and 14.

To further increase the bonding strength between the inner electrodes 25 and 26 and the respective outer electrodes 13 and 14, the connecting portion 18 preferably contains the same metal as that contained in the outer electrodes 13 and 14 and the same metal as that contained in the inner electrodes 25 and 26. The connecting portion 18 more preferably contains the first metal component and the same metal as that contained in the inner electrodes 25 and 26.

Preferred embodiments of the present invention will now be further described in detail based on specific non-limiting experimental examples. However, the present invention is not limited by the experimental examples below and may be modified without departing from the scope of the present invention.

Ceramic electronic components each having the same structure as that of the ceramic electronic component 1 according to the above-described preferred embodiment were prepared under the conditions below. For each of the conditions, 5000 ceramic electronic components were prepared. Subsequently, the insulation resistance between an outer electrode and an inner electrode was measured under the conditions below. Samples having an insulation resistance of 100 MΩ or less were defined as poor samples, and the number of poor samples were counted. Table 1 shows the results. In this experiment, insulation resistance was used as an index of the bonding strength between the inner electrode and the outer electrode. Herein, the following phenomenon is used. When the bonding strength between the inner electrode and the outer electrode is low, that is, when the contact resistance between the inner electrode and the outer electrode is high, the charging rate of a capacitor decreases. In the case where a capacitor is charged within a short time, the charge is completed in samples having low contact resistance and the flow of electric current stops. Consequently, a high resistance value is measured. In contrast, the charge is not completed in samples having high contact resistance and the flow of electric current continues. Consequently, a low resistance value is measured.

The length of a connecting portion was measured as follows. First, three samples were picked out from each of the sample groups. For each of the samples, about half of the volume of the sample was polished in the width direction so that the LT cross section shown in FIG. 2 was exposed. Subsequently, the LT cross section was observed with an electron microscope, and the lengths of three arbitrary connecting portions located in about half of the samples in the T direction on one of the outer electrodes were measured. In such a manner, nine lengths were measured for each of the sample groups, and the average value of the nine lengths was defined as the length of the connecting portion. Table 1 shows the results. The reason why the lengths were measured on one of the outer electrodes is that there is assumed to be no large difference in the formation state of the connecting portion because a pair of outer electrodes are symmetrically formed. The reason why the lengths of three arbitrary connecting portions located in about half of the samples in the T direction were measured is that there is assumed to be no large difference in the length of the connecting portion in the T direction.

FIG. 7 is a photograph showing a partially enlarged cross section of a ceramic electronic component prepared in Experimental Example 8.

Size of ceramic body 10: 1.0 mm×0.5 mm×0.5 mm

Ceramic material: BaTiO₃

Thickness of ceramic layer 10 g: 1.90 μm

Material of inner electrodes 25 and 26: Ni

Thickness of inner electrodes 25 and 26: 0.61 μm

Number of inner electrodes 25 and 26: 156

Distance from outermost inner electrode to principal surface (thickness of outer layer on one side): 60 μm

Resin 17 c: thermosetting epoxy resin

Content of first metal filler relative to the total amount of first metal filler, second metal filler, and resin 17 c: 25.6% by weight

Content of second metal filler relative to the total amount of first metal filler, second metal filler, and resin 17 c: 60% by weight

Content of resin 17 c relative to the total amount of first metal filler, second metal filler, and resin 17 c: 14.4% by weight

Heat treatment atmosphere: nitrogen gas atmosphere

Heat treatment time: shown in Table 1

Heat treatment temperature: shown in Table 1

Second conductive layer 16: laminated body of Ni plating layer and Sn plating layer (Sn plating layer forms an outermost layer)

Measurement Conditions of Insulation Resistance

Charging voltage: 2.5 V

Charging time: 30 ms

Discharging time: 3 ms

TABLE 1 Heat Heat Length of Number of poor treatment treatment connecting samples/number temperature time portion of samples Experimental 450° C.  90 minutes  1.8 μm 1055/5000 Example 1 Experimental 450° C. 120 minutes  2.4 μm  606/5000 Example 2 Experimental 480° C.  30 minutes  3.1 μm  661/5000 Example 3 Experimental 500° C.  13 minutes  2.5 μm  798/5000 Example 4 Experimental 500° C.  18 minutes  2.8 μm  645/5000 Example 5 Experimental 500° C.  30 minutes  3.2 μm  457/5000 Example 6 Experimental 550° C.  13 minutes  2.9 μm  596/5000 Example 7 Experimental 550° C.  18 minutes  3.8 μm  606/5000 Example 8 Experimental 550° C.  30 minutes  5.2 μm  635/5000 Example 9 Experimental 550° C.  90 minutes  9.6 μm  386/5000 Example 10 Experimental 600° C.  13 minutes  4.6 μm  582/5000 Example 11 Experimental 600° C.  18 minutes  5.0 μm  600/5000 Example 12 Experimental 600° C.  30 minutes  5.3 μm  546/5000 Example 13 Experimental 650° C.  18 minutes  5.6 μm  463/5000 Example 14 Experimental 650° C.  90 minutes 11.2 μm 2119/5000 Example 15

As is clear from the results shown in Table 1, the number of poor samples is large in Experimental Example 1 in which the length of the connecting portion is 1.8 μm. It is also clear that the number of poor samples is large in Experimental Example 15 in which the length of the connecting portion is 11.2 μm. However, in Experimental Example 15, it is assumed that, as a result of excessive growth of the connecting portion, the connecting portion lifts up the first conductive layer and thus contact failure is generated. Therefore, this mode is believed to be different from that in Experimental Example 1. In addition to the Experimental Examples shown in Table 1, an experiment was performed at a heat treatment temperature of 800° C. However, in this experiment, the resin 17 c was scattered and thus the outer electrodes substantially did not contain the resin 17 c.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A method for producing a ceramic electronic component, the method comprising: a step of preparing a ceramic body that includes an inner electrode disposed inside the ceramic body and in which an end portion of the inner electrode extends to a surface of the ceramic body; a step of forming an electrode layer on the surface of the ceramic body so as to cover the end portion of the inner electrode, the electrode layer including a thermosetting resin, a first metal filler that contains a first metal component, and a second metal filler that contains a second metal component having a higher melting point than the first metal component; and a step of heating the electrode layer to form, on the surface of the ceramic body, an outer electrode that includes the thermosetting resin and the first and second metal components and that is disposed so as to cover the end portion of the inner electrode and a connecting portion that contains the first metal component and a metal contained in the inner electrode and that is disposed so as to extend from an inside of the outer electrode to an inside of the ceramic body; wherein the first metal component of the first metal filler has a melting point of about 550° C. or lower.
 2. The method for producing a ceramic electronic component according to claim 1, wherein, in the step of heating, the electrode layer is heated to about 480° C. or higher in a non-oxidative atmosphere.
 3. The method for producing a ceramic electronic component according to claim 2, wherein, in the step of heating, the electrode layer is heated to a temperature of lower than about 800° C.
 4. The method for producing a ceramic electronic component according to claim 1, wherein the first metal component contains Sn and the second metal component contains Ag.
 5. The method for producing a ceramic electronic component according to claim 1, wherein the inner electrode contains Ni. 